Today infrared technology is used in a multitude of purposes from heaters to imaging.
Infrared technology is most widely known for use in military and law enforcement for night filters or tracking of objects by their heat signature.
Every physical body – whether it is living or nonliving – gives off a certain amount of heat. This is known in science as the “Blackbody Radiation Law.” We can virtually “see” any object by theheat emitting from that object. You may have seen night vision goggles in movies or in person – allowing the user to see at night by tracking the heat of an object. Thermography is the method that scientists use to measure the temperature of objects. Infrared is used in imaging of digital cameras and cell phones as well as in different types of communications. You will find infrared technology in spectroscopy, climatology, astronomy and interestingly, in art history. Art historians use infrared technology on old paintings to determine if there is a hidden underlayer to paintings or works of art. For our purposes, we focus only on the heating value of infrared for this book. I will discuss different methods of heating either through ceramic or carbon fibre heaters later on.
The International Commission on NonIonizing Radiation Protection (ICNIRP) (2006) published a statement exploring infrared exposure on humans with respect to biological tissues. It gives a solid definition of infrared rays along with excellent graphs and descriptions of infrared wave penetration at various wavelengths. The ICNIRP statement also gives a clear explanation of how infrared waves as produced in saunas affect the skin, eyes, and other biological tissues. It states adequate exposure times and gives a caution to using an infrared sauna if one has skin cancer.
Finnish saunas and other conventional hot air saunas heat only the air around them at high temperatures between 150-500° F. An Infrared sauna produces infrared waves at lower temperatures that penetrate the skin to approximately 1.5” or 3.81 cm, increasing the body’s temperature internally and more quickly than merely sitting in a hot environment. Infrared saunas provide greater benefits at lower temperatures resulting in more effective sauna sessions for the user.
Heaters used in infrared saunas emit approximately one third of their waves in the middle to intermediate portion of the infrared band of the electromagnetic spectrum: 2 to 5.6 microns. However, what makes them so effective is that two thirds of their emission falls in the deep body penetration range of 5.6 to 25 microns- with the average wave length being 9.4 microns- which happens to be the optimal point for human heating output (Flickstein, 2000).